The influence of ethanol as a solvent on the gibberellic acid-induced germination of Brachyscome and Allittia (Asteraceae) seeds

Abstract

Gibberellic acid (GA₃) is routinely used as a germination stimulant for seeds. However, the methods used to dissolve GA₃ powder – particularly if using organic solvents – have the potential to affect germination outcomes. In this study we examined the influence of the solvent ethanol, used to dissolve GA₃, on the seed germination of 14 species of Brachyscome and two species of Allittia. These species are important Australian native composites with potential for use in habitat restoration. Seeds of 11 of these species were found to be particularly responsive to GA₃. However, the use of a low concentration of ethanol (0.5%) to dissolve GA₃ affected subsequent germination outcomes, with four species responding positively and eight negatively to this solvent. The pure effect of GA₃ was therefore masked by the presence of small concentrations of ethanol, whose effects varied between the species examined. Because of these potentially confounding effects of ethanol, we recommend the use of pure water for dissolution of GA₃ when testing seed germination responses in these genera.